Bench-scale Development of a Transformational Graphene Oxide-based Membrane Process for Post-combustion CO<sub>2</sub> Capture

Graphene-based materials, such as graphene and graphene oxide (GO), have been considered as next-generation membrane materials. GTI Energy and The State University of New York at Buffalo (UB) have been developing a transformational GO-based membrane process (designated as GO2) that integrates a high CO2/N2 selectivity membrane (GO-1) and a high CO2 flux membrane (GO-2) for post-combustion CO2 capture. An innovative membrane structure, consisting of GO nanochannels intercalated by single-walled carbon nanotube (SWCNT), was developed. The membrane prepared on hollow fiber substrate showed CO2 permeance as high as 1,300 GPU with CO2/N2 selectivity >200. The membranes were successfully scaled up to effective area of 50-100 cm2. The 50-100 cm2 membranes showed CO2/N2 selectivity ≥200 and CO2 permeance ≥1,000 GPU for the GO-1 type, and CO2/N2 selectivity ≥20 and CO2 permeance ≥2,500 GPU for the GO-2 type. The CO2 capture performance of the GO-based membranes was tested using a simulated flue gas. The testing results indicate that the GO-based membranes are stable in the presence of flue gas contaminants. The GO-based membranes were then further scaled up to a surface area of 1,000 cm2. Good stability was achieved during an integrated testing with GO-1 and GO-2 membranes using simulated flue gas. A bench-scale system was designed, constructed, and tested at the National Carbon Capture Center (NCCC). Good stability was achieved during testing of a single-stage process with >10 shutdowns/startups at NCCC. During the integrated testing, the membranes showed good stability at 50°C and 57°C. 70-90% CO2 removal efficiencies and ≥95% CO2 purity were validated during the steady state operation at NCCC. Techno-economic analysis indicates the GO2 membrane-based process technology provides a reduction in both the levelized cost of electricity (LCOE) and cost of capture when compared to the reference B12B case presented in the Cost and Performance Baseline for Fossil Energy Plants Volume 1: Bituminous Coal and Natural Gas to Electricity study prepared by the National Energy Technology Laboratory (NETL), before considering any system optimization or improvement opportunities. The benefits are primarily driven by a reduction in the equipment costs of the CO2 capture process vs. the solvent-based reference process in NETL Case B12B as well as a decrease in the base plant size.